Permaculture is a gestalt ... a study of the whole. Not just how to produce more and better food, but how human life on the planet affects and is affected by the surrounding environment.
Bill Kearns http://columbiabasinpermaculture.com

We are calling the first wofati "version 0.7 beta". Well, I decided to call it that. This is a bit of a throwback to my old bananacom stuff. I uploaded "version 0.7 beta" to compuserve in 1993 or 1994 and in less than 24 hours I found that I had created a big winner.

Plus "version 0.7 beta" implies "this is an unfinished experiment." What we learn from this will help us to make a better version 0.8 and then move on to create version 1.0.

Tim Skufca and I spent about an hour talking about an edge detail and i think we came up with an excellent solution. Jesse is bringing in a long list of details to make a special kind of sketchup that shows progression. Plus, I think what will be great is that once Jesse's stuff is well polished, it will be good to make some sort of video out of Jesse's drawings.

Ten poles are now in the ground. My brother, Tim Wheaton, is ready to start construction of the next phase but thinks it would be wise to get all the brains in agreement on how to use a chainsaw for the joinery. So Caleb Larson, a local timber framer who has been in several of my podcasts (including the one on roundwood timber framing) is chomping at the bit to see Jesse's sketchup, make suggestions and will be out here in a few days.

I realize that plans such as this are not a literal final product, and technicalities and details get worked out along the way by the common sense of the builders. But I have a few questions that come to mind based on the drawings.

1. Will the roof be covered in dirt? If so, how will you keep it up there and still allow water drainage? I ask because it seems typically that an earth roof runs into the earth berm and you have an uninterrupted "dirt flow" that holds itself in place and lets water flow through the soil naturally. This design appears to have the roof elevated from the ground all the way around.

2. Will you backfill dirt against the sides and down-hill side? If so, what are you planning to use for siding/shoring material? I've never heard Mike admit or even acknowledge it, but his "approved design" of using 2x6 tongue and groove siding *always* fails, even on spans as small as 4 feet, and even with a soil depth as low as 3 feet. Thin walls like that always bulge in. Bulging means there was movement. Movement creates a high risk of perforating the waterproofing material. And bulging walls are ugly, and a bit scary. This design here shows 10 foot spans. The pictures of the actual site don't indicate much of an excavation, so maybe the sides won't be very deep into the ground on the actual structure?

3. The design looks like it will be dark inside. But perhaps the building won't be as far underground as the drawing shows?

4. What kind of discussions have been going on regarding the "ATI" part of WOFATI? Will you spread out an "umbrella" around the structure? What about use of earth tubes and that sort of thing?

Edward, have you perused Paul's original article on wofati? If you haven't, you might get some of your concerns addressed there. I saw a video with one of Mike Oehler's houses in it--it was decades old and hadn't failed, far as I could see. Maybe if you keep the earth on the outside of the wall dry you don't get the problems you are predicting. I haven't built one of these myself, but I can't wait to see how it goes!

Ed, I agree, Oehler's design of the tongue and groove shoring seems inadequate, (for the roof decking as well). Tim Wheaton (Big Tim) and I discussed the roof decking, which will be a series of 6 to 8" diameter logs filled in with 2 to 4" diam. logs. The tips and butts will be alternated, with the small logs filling in where needed. I imagine a similar system for the wall shoring with each course pinned where possible. If a smoother wall surface is desired, I know the mill is churning out some material that could work, but, as you point out, the 10 foot span is too great of a span for 2x material. I would suggest maybe two intermediate posts to break up the span.

Paul, as far as your critique on the wing-wall design, the Sketch-up drawing doesn't show too well that there is a 5 foot overhang over the gable. This should adequately protect the front two log posts and the shoring wall. The series of vertical log posts at the end of the wing wall would basically be sacrificial logs. This is the same design that is detailed in Sepp Holzer's Permiculture book, pages 96 - 100. These posts will last several years, and are there mostly to protect the rest of that wall by supporting the overhang. The angle of these wing-walls from the main structure should relate to the site, and the amount of fill required.

Of course, this issue would not exist if the use of concrete was allowed. This brings up a question: could the use of the diesel-powered track-hoe be swapped for some key areas where it's hard to beat concrete? [remember, the Romans used grout that still is holding structures today] Just thought I'd add a little fodder to the forum.

Tim Skufca

Posts: 64

19

posted 5 years ago

1

Jesse Biggs wrote:Here's a boat load of images we've been working with:

Jesse:
Your mastery of the Sketch-up program is impressive. These images are very helpful. There are a few details I'd change, though. I don't believe the double posts at the floor-level change is necessary. I know you followed Oehler's detail for the bottom purlin over the four lower posts of the 10x30 area, but if that purlin matched the others up hill from there, then the two perpendicular purlins that top the walls of the gable could share the same post for support, rather than adding another post. Doing this solves an issue I see in your sketches that has a gap at these two corners. What helps this is to put the ridge of the gable support higher up the slope (on the second purlin upslope). This also gives a steeper slope for the gable which would match the 36" in 10' (3.6"/12") slope of the other part of the building.

One last detail, the 5 foot overhang is important for protection and a knee brace is needed to accomplish this length. The ridge beam will also require a knee post, which couldn't be possible in your sketch. That is why I lowered the beam across this gable so that it could accept a knee brace.

I have a really crappy computer right now, and I am gonna return this one and get a different one. If my computer were in better condition I might try to install sketchup and have a go. But, as is, if Jesse is okay with it, I would like to see the sketchup of what is in my head. I am thinking that the slope to the ground would be shorter, the retaining wall would be smaller, and the wood in the retaining wall would be less/smaller - thus easier.

As for cement: I have a lot of goals for this structure. Including using as much material as possible from the local trees. If we can do it with wood from the land instead of cement, I am very much in favor of that.

paul wheaton wrote: I am thinking that the slope to the ground would be shorter, the retaining wall would be smaller, and the wood in the retaining wall would be less/smaller - thus easier.

I agree, if this wing-wall were shorter, then less fill would be needed to be hauled in. However, the Sketch-up drawings do not reflect the actual site. There is hardly a slope which will require a lot of fill to cover the structure. Jesse's drawings, on the other hand, represent a site with a considerable slope, thus a need for longer wing-walls.

I would propose, if Sketch-up has the ability, to place the 0.7 WOFATI in real conditions and determine how much fill is going to be needed. This would be a good figure to give to Big Tim to determine where this material will come from.

I would like Jesse to focus on "standard wofati on a normal-ish slope". Once that is excellent and shiny we can talk about possibly modifying it to fit this particular circumstance. For the retaining wall at the downhill slope I think it won't make much difference because that will all be dirt that we have moved into position.

Tim S., I'll work on the changes. I have a concern with having the 4 purlins you mentioned sharing the same post. My concern is that the joint could get too complicated and thus become complicated to construct. It looks to me like the uphill/downhill purlins all go onto the posts first, then the beams are set in place. In this scenario, the joint where the shed meets the gable will have purlins coming together at 2 different angles, an then a beam will be secured over top of them. I don't have much framing experience, but wouldn't that mean 2 fasteners into the supporting post, and how then would the beam above be safely fastened to this compound joint? Maybe there is a simple way of fastening this all together, but it's outside of my knowledge set, thus my attempts to do something different.

Paul, I'm happy to keep working on this as I can. It's fun and I want to wrap my mind around it. Unfortunately, the going will be a little slow for me right now. Two things I could use clarification on... what do you mean by:

I would also like the retaining logs to be far back from the roof wood.

Are you talking about the retaining logs on the "winglike" bits, or the uphill patio?

also:

I am thinking that the slope to the ground would be shorter, the retaining wall would be smaller, and the wood in the retaining wall would be less/smaller - thus easier.

is

Does this mean that the overall structure is sitting more above ground thus meaning less of a need to retain earth?

I'm sitting here thinking that it makes sense to do what Mike describes in his book. That is, decide where your downhill retaining walls are going on the given site and backfill against them as you excavate uphill. I'm a little confused why there will need to be fill brought in. Is it because there's very little slope and 0.7 is sitting a little more "proudly"?

It IS possible to bring a rough topo in from google earth, but in my experience it's not that accurate on a micro scale such as a 400 sq.ft. structure, and it makes the model a bit more complicated thus slowing things down.

I would also like the retaining logs to be far back from the roof wood.

Are you talking about the retaining logs on the "winglike" bits, or the uphill patio?

I am focusing, for the moment, on the wing-like bit on the downhill side. Once we have that perfected, then we can rubber stamp it to the other side. I want the roof-ish stuff on the gable roof to come down to the ground, but a bit more downhill than the gable roof line. Then the retaining wall stuff sits well within that shelter, thus keeping those woody-bits dry.

also:

I am thinking that the slope to the ground would be shorter, the retaining wall would be smaller, and the wood in the retaining wall would be less/smaller - thus easier.

is

Does this mean that the overall structure is sitting more above ground thus meaning less of a need to retain earth?

A wofati house is always above ground. Therefore, for the slope that you have defined in your drawing, the dirt will come from on site. In the case of this actual build, the slope is pretty shallow, so we will be importing dirt to keep the structure above ground.

For the one little retaining wall segment, I would like to get that drawn up with your existing slope. I think the way I am proposing is what Tim S. and I discussed a few weeks ago and will be excellent. Once it is drawn, then I can talk to tim about how he might want it to be different and why.

Jesse Biggs wrote:I'm sitting here thinking that it makes sense to do what Mike describes in his book. That is, decide where your downhill retaining walls are going on the given site and backfill against them as you excavate uphill. I'm a little confused why there will need to be fill brought in. Is it because there's very little slope and 0.7 is sitting a little more "proudly"?

It IS possible to bring a rough topo in from google earth, but in my experience it's not that accurate on a micro scale such as a 400 sq.ft. structure, and it makes the model a bit more complicated thus slowing things down.

Yes. The idea is to have this more above ground than an oehler structure.

Maybe a future wofati site will have more slope and we won't need to bring in more dirt. In the case of the current wofati, we will probably bring the dirt in from 50 feet away. Not a big deal.

I think the need to be above ground is bigger than the need to use dirt that was at ground zero.

Hello,
If I could make a few suggestions. The design (in Sketchup) could be saved and copied and then readjusted to accomodate various sloped land(s).
For example, Design 1 could be for 0-2% slope, Design 2 could be for 2-4% slope, etc.
The idea being to have a balanced design in the sense of earthmoving, meaning that you try to make the net cut/fill as close to zero as possible.
This way, when you are at a site, all you need to determine is what the existing slope of the area is and then you can select the design that matches the exisitng slope.
Some local topographic information is always the best thing to start with, but that may not be so easy to obtain.
If you would like some demonstration of this, I can try to help.

Hope this helps,
-Kevin

Tim Skufca

Posts: 64

19

posted 5 years ago

Kevin Murphy wrote:Hello,
Some local topographic information is always the best thing to start with, but that may not be so easy to obtain.

Hey Kevin,
Thanks. Yes, your idea of having patterns of cut/fill requirements for a WOFATI is a great idea. There would need to be some extrapolations made since every WOFATI will most likely be different.

I measured the slope at the WOFATI 0.7 site which is 1" in 12" - very shallow, which means a significant amount of fill compared to the cut.

Hi Tim,
1" on 12" is about 8.3% slope. 8% over 50 feet would be 4 foot change in elevation.
I think you may want to try measuring a longer distance to check the slope calculation.
Of course I live in the coastal plain of NJ where 8% is steep. Where you are working, 8% might seem flat.

I do understand that each structure will be different, but with some basic assumption the earthwork can be balance so that minimal earth moving is required.
I might also suggest that we look at the soil type and include some data on how the soil load will effect the structure as well.

Hope this is helpful
-Kevin

Jesse Biggs

gardener

Posts: 213

Location: 40N 112W On the Edge Between the High Steppe and High Desert

Kevin, I attached the model I've been working with above. It'd be great to have lots of people fiddling with it. The files could even be shared to google's 3d warehouse where we might infect more brains.